anthropogenic forest change in the 21 st century a warning to policy makers or a foretaste of things...

Anthropogenic Forest Changein the 21st century

A warning to policy makersor

a foretaste of things to come?

Litany of factors forcing change in tropical forests

• Burning the unburnable• Logging synergizes fire• Roadbuilding• Fragmentation and edge effects• Rising sea surface temperature lifts the cloud bank• Deforestation alters local climate• Accelerating turnover• “Idiopathic” compositional change• Compositional instability of the “empty” forest

Burning the unburnable

Logging synergizes fire

Roadbuilding synergizes logging

Models of development in the Amazon. Optimistic (top) and nonoptimistic (bottom) scenarios, showing predicted forest degradation by the year 2020. (Black is deforested or heavily degraded, including savannas and other nonforested areas. Red is moderately degraded, yellow is lightly degraded, and green is pristine).

Laurance et al. 291 (5503):38-- Science

Fragmentation and edge effects add to the risk of fire

Rising sea surface temperature implicated in amphibian

extinctions

Deforestation alters local climate

Turnover of tropical forests has accelerated globally

“Idiopathic” forest change

“Empty” forests are compositionally unstable

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Densities of seed dispersers and seed predators atCocha Cashu Biological Station and Boca Manu, Perú

EBCC BMDispersers, diurnal No./km2 No./km2

Primates, large (spider, howler) 13.2 0.0Primates, mid-sized (capuchins) 61.1 5.5Primates, small (titi, squirrel, tamarins) 43.6 26.3

Birds, large (guans, trumpeter) 22.7 2.3

Dispersers, nocturnal

Mid-sized (kinkajou, night monkey) 28.1 29.8

Seed predators, diurnal

Large (white-lipped, collared peccaries) 179.9 30.5Mid-sized (agouti, acouchi) 26.6 11.8Small (squirrels) 39.0 30.2

EBCC vs BM: Number of Trees 10 cm dbh, by Dispersal Syndrome

0

100

200

300

400

500

600

700

Bat Bird Primate Rodent Wind UnknownDispersal Syndrome

Num

ber

of T

rees

10

cm

dbh

EBCC: Number of Trees BM: Number of Trees

EBCC vs BM: Number of Small Saplings per Hectare

0

100

200

300

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500

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700

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900

Bat Bird Primate Rodent Wind UnknownDispersal Mode

Num

ber

of S

aplin

gs

EBCC: Number of Small Saplings BM: Number of Small Saplings

Winners DispersersAspidosperma megaphyllum WindFicus maxima BatsVirola calophylla Birds, primatesNeea RF#5005 BirdsNectandra longifolia BirdsCaraipa densiflora WindPourouma minor PrimatesDiospyros subrotata PrimatesUnonopsis mathewsii Birds?Inga acreana Primates

Losers DispersersMaytenus magnifolia PrimatesRheedia brasiliensis PrimatesZizyphus cinnamomum PrimatesMatesia cordata PrimatesLicania britteniana PrimatesIryanthera olacoides Bats?Calatola microcarpa PrimatesPouteria trilocularis PrimatesChrysophyllum venezeulelanaPrimatesTrichilia septentrionalis Birds?

Winners and Losers at Boca Manu

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2147

10131619222528313437404346495255586164

Log

BM/E

BCC

Log Values (Ranked)